Carburetor



May/122,v 1,945- R; R. STREBINGER 2,376,732

' GARBURETOR Filed July 5, 1941 36 54 Z0 37 39 Z/k IVN VEN TOR Y ,9c/Meo,Q 57am/Nase A TT ORNE Y pedal of the automobile.

Patented May 22, 1945 C Richard E. Strebinger, South Bend, Ind.,assignor to Bendix Aviation Corporation, South Bend,

Ind.. a corporation o! Delaware I Applicationlllly 5, 1941, Serial No.401,170

This invention relates to carburetors and more particularly to means forcontrolling the throttle valves in multiple stage carburetor systems forinternal combustion engines. Certain subject matter oi' this applicationhas been divided here from and is now being claimed in applicantscopending application Serial No. 542,978 led June 30, 1934.

Multiple stage carburetorsystems for widely variable speed internalcombustion engines such as are commonly used in automotive vehicles andthe like may comprise either a plurality of separate carburetors or 'asingle carburetor having a plurality of induction passages. In eitherarrangement there are a plurality of induction passages connected to acommon intake manifold or4 to complementary manifolds, throttle valvesfor the respective induction passages, and means for contr'ollihg thethrottle valves whereby they are k opened progressively.

'I'he general purpose of this type of carburetor /system is to supplythe engine with an economical fuel mixture from a primar;T source, whichmay comprise one primary induction passage or a plurality of saidpassages, throughout the lower speed range which in an automobile engineis used to the greatest extent, and to supply the engine with asupplementary mixture from one or more supplementary or auxiliaryinduction passages at speeds above said lower speed range, therebyincreasing the volume of the mixture'delivered to the engine t0 permitsaid engine iclsim. (oreal-2?.)A

have not proved entirely satisfactory incontrolling a carburetor systemof the multiple stage type so as to accurately meet the fuel mixturerequirements of the engine under all operating conditions.

Among the automatic controls for the throttle valves of stagessubsequent to the primary stage are various types of suction responsivemeans v which may be connected to one or more of the to develop itsmaximum speed and power.1 This involves closing on' the supplementalpassage or passages when the engine is operating under low speed wideopen throttle conditions, in order to furnish the engine with a mixtureof combustible proportions under such conditions and permit very lowspeed operation without misfiring orJ stalling. The reason the enginewill operate at lower speeds Without missing when supplied with fuelmixture by one induction passage than when thus supplied by a pluralityof passages-is that the velocity of the air owing to the engine throughone passage is greater than if the same volume of air were ilowing tothe engine through a greater number of passages, and with greatervelocity the air picks up more fuel and sustains said fuel until itreaches the enginel cylinders.

'I'he throttle valve for the primary induction passage or ilrst stage ismanually controlled, being customarily connected with the acceleratorVarious means have been employed to automatically control the remainingthrottle valve or valves lout such means induction passages. f Incarburetor systems using such vacuum responsive means for opening thethrottle valves of supplemental induction passages, diillculty issometimes encountered in effecting the closing of said valvesparticularly after said valves have been opened to a substan tialdegree.

It is therefore an important object of the invention to providein amultiple stage Vcarburetor system means for controlling the volume andfuel-to-air ratio of the fuel mixture according to the requirements ofthe engine throughout its operating range.

It is a further object of the present invention to provide means for'effecting proper closing movement of the supplemental throttle valvesof a multiple stage carburetor system employing automatic `means foropening said valves; upon decelerating movement oi' the acceleratormecha nism. Still another object of the invention is to provide -adevice of this character wherein the throttle valves of supplementarystages are controlled by the position of the throttle valve of a preiceding stage.

A further object of the invention is to provide a device of thischaracter wherein the supplementary throttle valve or valves willnormally be closed during the starting operation of the engine.

A still further object of the invention is'to provide a device of thischaracter wherein the supplementary throttle valve or valves will bepositively closed upon closing of the primary throttle valve.

The characteristics and advantages of theinvention are furthersufficiently referred to in conncection with the followingdetaileddescrlption of the accompanying drawing which represents certainpreferred embodiments. these examples, skilled persons will understandthat many variations may be made without departing from the principlesdisclosed, and I contemplate the employment of any structures, ar-

rangements or modes of operation that are properly within the scope ofthe appended claim.

After considering The drawing diagrammatically illustrates an internalcombustion engine provided with a multiple stage fuel induction systemembodying the present invention, said system comprising a plurality ofindependent carburetors shown in vertical section. l

While the invention is shown and described embodied in a multiple stagecarburetor system having one primary and one supplemental or secondaryinduction passage it may also be embodied in such a system having aplurality of both primary and supplemental induction passages or a,single passage for one stage and a plurality of passages for anotherstage or stages. It may also be-embodied in a system of this characterwherein the engine has a dual or multiple type of intake manifold, eachpart of which has connected therewith corresponding primary andsupplemental induction passages.

Referring to the drawing reference numerall I indicates the engine andI2 the intake manifold thereof having a primary carburetor P and asecondary carburetor S attached thereto. The respective carburetors Pand S comprise air horn sections I4 and l5, body sections I6 and |1, andthrottle body sections I8 and |9. 'I'he induction passages of saidcarburetors include air entrances 20 and 2|, small venturis22 and 23,large venturis 24 and 25, and mixture passages 26 and 21 respectively.Acceleration pumps 28 and 29 and economizer systems 30 and 3| areprovided in the respective primary and secondary carburetors, saideconomizer systemsl including a valve 32 and vacuum responsive means 34controlling said valve.

'I'he respective air entrances 20 and 2| are ccntrolled by the usualunbalanced choke valves 36 and 31 on shafts 38 and 39, said valves beingcontrolled by manual or automatic means, not shown, and the mixturepassages 26 and 21 are controlled by respective throttle valves 40 and4| on shafts 42 and 43. The choke valve 31 may be omitted if desired.The primary and secondary earburetors have idling systems 44 and 45respectively and mainfuel nozzles 46 and 41 supplied with fuel from fuelchambers 48 and 49 and discharging in the respective small venturis 22and 23, in the known manner.

' The primary carburetor is provided with-a fast idle mechanism one typeof which is illustrated in the drawing and which includes a fast idlecam 50 pivoted at 52 and connected with a choke valve leve'r 54 on shaft39 by a rod 56. 'I'he cam 50 is engageable with a screw 58 in anextension of primary throttle lever secured to one end of the shaft 42,said lever 60 being connected with the usual accelerator pedal or otheroperatingv member, not shown, by rod 62.

Automatic suction responsive means for ,actuating the secondary throttlevalve 4| is provided and, as shown, comprises shell or asing members |56and |58 having a flexible diaphragm |60 clamped therebetween with rod|62 extending therethrough and iixed thereto in sealed relation by anysuitable means which in the present dis- .closure comprises a nut |64which clamps the packing gland |18 to prevent leakage of air past theplunger. Within the sleeve |14 is a dampener spring I which reactsbetween the closed outer end |82 of 4said sleeve and the adjacent end.of rod |62 and has a cushioning eiIect therebetween. Another spring,|88, is provided to react between the casing member |86 and washer |68urging the diaphragm to the right, as viewed in the drawing, and isadapted to yieldingly effect closing of the throttle valve 4'.

The control unit for the secondary throttle valve is divided by thediaphragm into two parts, a chamber |84 which is exposed to atmosphericpressure by means of opening |12 and a closed chamber |86 which isconnected to the small venturis 22 and 23 of the primary and secondaryinduction passages respectively by conduits |88, |90 and |92 so that thepressure in chamber |86 is the resultant of the pressures in the smallventuris of the primary and secondary induction passages.

Means for effecting closing of the secondary throttle valve 4| includesa lever |94 pivoted at |96 and having a rounded projection |98 adjacentone end thereof which is engageable with the free end |82 of plunger |14and which provides a one way connection limiting outward movement of theplunger relative to the chamber |86, the lever |94 being connected tothe primary throttle lever 60 by alink 200.

Operation of the embodiment of the invention shown in the drawing is asfollows:

When the primary throttle valve v40 is in the closed position plunger|14 is urged inwardly of the chamber |86 by lever |94 therebycompressing spring |80 which aids spring |89 in urging the secondarythrottle valve to the closed position and said springs normally retainthe secondary throttle valve in said position during the starting periodof engine operation and at other times as hereinafter described.

Throughout the lower speed range of the engine it is normally suppliedwith fuel mixture only by the primary induction passage.. As the primarythrottle valve 40 is opened, the end of lever |94 having the projection|98 is moved toward the left as viewed in the drawing, -whereupon spring|80 expands and causes the plunger |14 to move outwardly relative tochamber |86. However, the outward movement of said plunger is limited bythe projection |98, andthe force of the spring |80 on the end o! rod |62combined with that of spring |83 is sufficient to retain the secondarythrottle valve in the closed position ferred to in the next precedingparagraph, is

effected by means of the conduits |88, |90 and |92 connecting saidchamber with the small venturis of the primary and secondary inductionpassages respectively.

When the primary throttle valve 40 is in the idling position there isbut slight reduction of pressure in the small venturi 22 of the primaryinduction passage which is diminished by air bled through conduit |92.Upon opening movement of the valve 40 the engine speed increases therebypermitting increased air ow through the primary induction passage whichresultsin in-Y creased suction in conduit |90, however theair bledthrough conduit |92 prevents sufficient reduction of pressure in chamber|86 to permit atmospheric pressure in chamberld to effect opening of thesecondary throttle valve against the force of springs |88 and |83 untilthe primary throttle valve has been opened the'predetermined amountWhereat the engine speed will be above said lower speed range. When thethrottle valve 40 has been opened said predetermined amount thereduction of pressure in chamber |86 is such that. the secondarythrottle valve 4| is initially opened by atmospheric pressure on thediaphragm |68 and further opening o'f the primary throttle valve 48 willeect further opening of the secondary throttle valve due to theincreased velocity of air in the primary induction passage and to thesuction which occurs in the secondary induction passage after thesecondary throttle valve is opened. As the secondary throttle valveopens, bleeding of air through conduit |92 di-4 minishes as the suctionin the secondary induction passage increases, thereby increasing thesuction transmitted to chamber |86 to aid in further opening of thesecondary throttle valve. Should the engine now be placed undersufficient load to greatly reduce its speed the velocity, of air in theprimary and secondary induction passages will decrease accordingly andupon sufficient reduction of speed the suction or vacuum in lsaidpassages will decrease to a value whereat the pressure in chamber |88will rise and approach atmospheric pressure whereupon springs |80 and|83 will have suflicient force to close the secondary throttle valve 4|and the engine will' then be supplied with fuel mixture only by theprimary induction passage.

However, when the engine is operating at high speed With both throttlevalves open and itis desired to decelerate, closing movement of themanually operable valve control mechanism will effect closing movementof both primary and secondary throttle valves. As the primary throttlevalve is closed the flow of air through the primary induction passage isreduced resulting in a cor- A throttle valve lever |94 urges plunger iminresponding reduction of suction in chamber |88. Simultaneously withthe closing of the primary wardly of the chamber |86 and compressesspring |80 and increases the closing force thereof on the rod |62 andthe linkage connecting said rod with the secondary throttle valve. Thecombined effect of the reduction in suction in chamber |88, theincreased closing pressure of spring |80 and the force of spring |83results in closing of the secondary throttle valve which is fully closedthereby before the primary throttle valve is fully closed. It is to benoted that in the absence of the mechanism for closing the secondarythrottle valve closing of the primary throttle valve might not effectclosing of lthe secondary valve due to the suction in the secondaryinduction passage which may remain sufliciently high to overcome theclosing force of spring |83 even though air is `bled to the controldevice through conduitl |98. Further it should be noted that the closingmovement of lever |98 is such that substantially full compression ofspring |88 will be effected when the secondary throttle valve is in anopen position and as a result said lever will positively eiect closingof the secondary throttle valve when the primary throttle valve isclosed.

It is thought that the invention and many of its attendant advantageswill be understood from the foregoing description and though saidinvention has been illustrated and described herein in connection withbut a single embodiment it will be apparent that various changes may bemade in the form, construction and arrangement of the parts withoutdeparting from the spirit and scope of the invention or sacricing all ofits material advantages.

I claim:

In a multiple stage charge forming device having a primary inductionpassage, secondary induction passage, and a throttle valve in eachpassage: means for controlling the primary throttle valve; suctionresponsive means vfor controlling the opening of the secondary throttlevalve; said suction responsive means being connected to both inductionpassages; and yielding means connected with the means for controllingthe primary valve for closing the secondary valve.

RICHARD R. STREBINGER.

